If you want a peek at the biggest challenge facing NBC anchor Brian Williams and his newsmagazine Rock Center, look no further than Mariah Carey's twins. • The TV debut of those 6-month-old babies — along with mama Carey, daddy Nick Cannon and interviewer Barbara Walters — helped power ABC's 20/20 to some of its best ratings in years on Oct. 21. • That's how today's newsmagazines often earn success: celebrity revelations, true crime stories and coverage of tabloid-tinged "soft" news. • So why is Williams leading the first new network TV newsmagazine to debut in nearly 20 years, with the mantra of being "a showcase home for quality journalism?"

"All we've been told, is to go and do the kind of broadcast we'd like to watch," said Williams, speaking during a telephone conference call last week. "There's no benchmark, there's no numbers, there's no ratings. Our charge was to put together the best broadcast of its type we could, get on the air and stay there."

As an example, the anchor recalled a moment when the Arab Spring exploded in Cairo, Egypt, forcing him and correspondent Richard Engel to hang back on a hotel balcony for fear of ricochets from a gun battle below. "We were on MSNBC all night," Williams said. "It would have been great to additionally have a broadcast network platform … (because) for those watching, it made for some incredible television."

He's enough of a news nerd to know this is music to a critic's ears.

For those of us charged with sifting through the latest Casey Anthony update or Lindsay and Michael Lohan breaking news, the idea of a prime time showcase for well-done TV journalism that isn't named 60 Minutes sounds like a pretty good idea.

NBC News executives added all the right grace notes: They're spending money to cover newsy stories with a team of correspondents, including former CBS anchor Harry Smith, former ABC correspondent Kate Snow and former Nightline anchor Ted Koppel, who won't appear every week.

They're also tapping talent from other NBC newscasts, MSNBC and CNBC. Early reports indicate tonight's stories will include Chinese women having babies in the United States who become citizens, and a town in North Dakota where every able-bodied adult can get a job.

(It may already be paying off. Advertising Age magazine reported 30-second ads for Rock Center are going for $110,000; nearly twice what NBC charged for the now-canceled Playboy Club at 10 p.m. Mondays).

For a long time, Williams has been a well-rounded TV presence in search of a suitable outlet. He is witty enough to trade repartee on The Daily Show and substantial enough to ride out Hurricane Katrina in New Orleans' Superdome.

On Rock Center, Williams will introduce stories live, allowing a bit of his nonnews charisma to show.

Executive producer Rome Hartman said the broadcast "ought to feel like Brian's playlist. He was on his way to London to cover the royal wedding, got there, (immediately) turned around and went to Tuscaloosa, Ala., and covered that devastating tornado. He's not the managing editor of this program for nothing."

Hartman, who tried mightily to reinvent network news for Katie Couric as her first executive producer on the CBS Evening News, has some mixed experience here.

But news nerds may also remember network TV executives said similar things back in the 1990s, when newsmagazines replaced many hourlong scripted shows. Eventually, networks fell in love with their lower cost, turning to less lofty reports in snagging viewers.

And it's hard to forget the most recent time a struggling NBC tried creating a cheaper program at 10 p.m. as a bridge to local newscasts.

"This is another attempt to do what they thought Jay Leno was going to do at 10 p.m. and failed," said Andrew Tyndall, a New York-based network TV news analyst. "The problem with Leno was, they started out at five nights a week when they didn't know if one would work. And they had a host who didn't really want the job."

In Williams, NBC has the opposite. He is a host who wants the job so badly that he's willing to do it along with his regular gig, anchoring TV's top-rated network newscast, the NBC Nightly News.

And when he talks about the fun of pulling it all together, you only wonder briefly why network news' biggest name still sounds so surprised he has gotten a weekly prime time outlet for quality news reporting.

"We're hiring people to put journalism on television," he said. "You don't get to start something like this more than once or twice in your lifetime."